Treatment of aqueous dispersions



INVENTOR C. T. RO LAN D E M R Mad 3 0 E 8 22% K M 0 Filed April 26, 1950N u v TREATMENT OF AQUEOUS DISPERSIONS Jan. 5, 1954 I Char/es T Roland E@v a 3,02 1; N, All X1 1903:

Patented Jan. 5, 1954 TREATMENT OF AQUEOUS DISPERSIONS Charles '1'.Roland, Bethel, Pa., assignor to Hall Laboratories, Inc., Pittsburgh,Pa., a corporation of Pennsylvania.

Application April 26, 1950, Serial No. 158,220

30 Claims. 1

This invention relates generally to the treatment of aqueous dispersionsto control their viscosity and stability and more particularly to thetreatment of aqueous dispersions with alginate materials to control theviscosity and stability of the dispersion. Hereafter when I speak ofalginate materials and alginates without qualification I mean thewater-dispersible or so-called water-soluble alginates. It is well knownthat sodium alginate and other Water-soluble alginates are not trulywater-soluble as the term might imply but are water dispersible to formcolloidal dispersions, the viscosity of which increase markedly with theconcentration of alginate.

This application is a continuation-in-part of my copending applicationSerial No. 513,450, filed December 8, 1943.

The commercial desirability and usefulness of many aqueous dispersionsis much enhanced by controlling their viscosity and effectivelystabilizing the dispersion. This is true of both edible and inedibledispersions. For example, chocolate milk drinks are much more attractivecommercially if the cocoa particles from which they are made aremaintained in suspension and prevented from settling out of the body or"the fluid milk. Also, abrasive polishing compositions such as polishingcreams are more satisfactory if the abrasive powder from which theyobtain their effectiveness is held in suspension.

It has been proposed to use alginates, pectins and gelatin to stabilizesuch aqueous dispersions; however, it has heretofore been impossible toproperly control the viscosity and at the same time the stabilizingefiect to produce an entirely satisfactory product. Chocolate milkdrinks to which a suficient amount of any of these materials has beenadded to satisfactorily stabilize the dispersion is either jellied, orslimy or otherwise so modified as to be commercially undesirable.

I have found a process for treating such aqueous dispersions as aredescribed above by which I can satisfactorily control the viscositywhile at the same time effecting the desired stabilizing effect on thedispersion.

I have discovered a process of treating aqueous dispersions having asone constituent a watersoluble metal compound having the property ofmodifying the viscosity of an alginate dispersion or to which such awater-soluble metal compound has been added which process comprisesgenerally the steps of adding to the dispersion a molecularly dehydratedphosphate in an amount so related to the total metal in solution thatsome but not all of the metal will be sequestered leaving some availablemetal ions in solution and then adding a Water-soluble alginate to thedispersion whereby the free metal ions react with the alginate, theamount of free metal ions being 5 regulated that a portion only of thealginate will be reacted. The water-soluble alginate modifying metalions may be either naturally occurring in the dispersion (as in the caseof milk) or may be added for the purposes of my process.

I have found that the viscosity of alginate dispersions containing suchmetal compounds may be controlled by adding thereto or to the commercialpowder from which the dispersion is to be made a molecularly dehydratedphosphate such, for example, as the sodium phosphate glass, commonlyknown as Grahams salt, or a commercial form of Grahams salt such asCalgon, a form having a NazO to P205 ratio of approximately 1.1:1.

More specifically, my process consists in adding to a given aqueousdispersion, a water-soluble metal compound, a water-soluble molecularydehydrated phosphate and then adding the alginate material. Theconcentration of the phosphate compound in relation to the concentrationof the metal compound is adjusted so that apparently some but not all ofthe metal ions in solution will be sequestered or tied up in awater-soluble, complex negative ion by the phosphate compound, thusleaving at all times some available metal ions in the solution. Upon thesubsequent addition of the alginate material, these available or freemetal ions can react with the alginate material but the concentration ofthe available or free metal ions in relation to the concentration of thealginate material is so controlled that a portion only of the alginatematerial will be reacted with these metal ions; thus there will alwaysbe present some alginate material reacted with metal ions, some alginatematerial in its unreacted form and some metal ions sequestered ascomplex negative ions.

I have found that the viscosities of such alginate dispersions can beeffectively controlled within narrow limits of the desired viscositiesby the addition of such metal compounds and such phosphate compounds inthe manner just described or by the addition of the metal compound andthe phosphate compounds to the commercial powder from which thedispersion is to be made by the subsequent addition of water.

I have referred to sodium alginate as one of the water-solublealginates. I may use this particular alginate or any one or more of theother water-soluble alginates Whose viscosity in aqueous solution iinfluenced by the presence of metal ions such as, for example, potassiumalginate, lithium alginate, ammonium alginate or magnesium alginate, ora mixture of alginates of the group of metals comprising the alkalimetals, ammonium and magnesium.

I have found that the principal water-soluble metal compounds having theproperty of modhalt, nickel, and lanthanum. It is to be borne in mindwhen choosing one of these metals for the purposes of my invention thatonly those which are known to be non-toxic should :be used with productsdesigned for food.

While I have specified that metal compounds be added to the aqueousdispersion-or to the commercial powder, I have found that when theappropriate metal ions are naturally present in the aqueous alginatedispersion from the components, as in the case of calcium ions naturallyoccurring in milk, these metal ions will serve in my process without theaddition of a metal compound when the proper amount of the phosphatecompound is added, except when the naturally occurring metal ionconcentration is too low, in which case a lesser amount of metalcompound must be added to supply the deficiency.

I have stated that the phosphate compound for my process is awater-soluble molecularly dehydrated phosphate, and have specified thatit must sequester bivalent or trivalent metal ions, which ever isemployed, from the metal compound additive. The sodium phosphatecompounds which I have found to serve in my process are thewater-soluble rnolecularly dehydrated phosphates in the range fromlNazOzlPzOs (which is known as Grahams salt or sodium metaphosphateglass) to 2Na2O-:1P2O5 (which is known as tetrasodium pyrophosphate).Most of these compounds are characteristically glassy or amorphous inphysical structure, including those commonly called hexametaphosphates,tetraphosphates, septaphosphates, decaphosphates, etc. Thepyrophosphates are crystalline and are not as effective as the glassyphosphates. The tripolyphosphates can be obtained either as crystals oras glass and either is efiective. There are two water-solublecrystalline molecularly dehydrated phosphates in this range, however,which are not effective in my process, namely, sodium trimetaphosphate[(NaPOzh] and sodium tetrametaphosphate [Na4P4O12], because they do notexhibit the phenomenon of sequestration when freshly dissolved in watercontaining bivalent or trivalent metal ions, but their solutions dochange in time under certain conditions to produce a sequesteringreaction, at which time these phosphates will serve effectively in myprocess. Also there are crystalline sodium metaphosphates which arepractically insoluble in water, such as Maddrell salt [(l-TaPO3):rl andKurrol salt [NaPOsMz], which, not being soluble, are not elfective in myprocess but which, when solubilized (as can be done), become effective.Other water-soluble molecularly dehydrated phosphates than the sodiumsalts, such as lithium, potassium or ammonium salts, or solubilizedcalcium or strontium salts, are also effective in my process. Inparticular, the water-insoluble potassium Kurrol salt [(KPOsml whensolubilized, as by the addition or" sodium chloride (NaCL), is quiteeffective.

The accompanying drawing is a graph illustrating the changes inviscosity which can be obtained by adding sodium phosphate glass of1.1Na2O:PzO5 ratio to a 0.2% sodium alginate dispersion and to adispersion containing 0. sodium alginate plus 0.02% of calcium.

Referring now more particularly to the ac- 4 companying drawing, theordinate represents the viscosities of the dispersions, as expressed inarbitrar units "M as measured at 30 C. on a MacMichael viscosimeterusing a No. 30 Wire on a disk plunger, and the abscissa represents theamount of sodium phosphate glass, expressed in per cent by weight of thewater in the dispersion. 'Curve l represents the viscosity of a 0.2%

sodium valginate dispersion as affected by the addition of sodiumphosphate glass. Curve 2 represents the viscosity of a dispersion of a0.2% sodium alginate solution containing 0.02% calcium as affected bythe addition of sodium phosphate glass. From curve i it is seen that theviscosity of the sodium alginate solution is decreased only slightly bythe addition of sodium pho phate glass. The eiIect of adding 0.02% ofsoluble calcium in compound form to the sodium alginate solution i tomaterially increase the viscosity. However, when this solution ofincreased viscosity is treated With sodium phosphate glass the viscosityis reduced, as indicated by curve 2, to a value as low as the 0.2%sodium alginate dispersion treated only with the phosphate glass. Thecurves illustrate one concentration of sodium alginate but it is to beunderstood that the addition of sodium phosphate glass to dispersionscontaining different amounts of sodium alginate, or of sodium alginateand calcium, affects the viscosity in a similar manner. For a givensodium alginate concentration there is a proportionate calciumconcentration, usually around 1:15 calcium to sodium alginate ratio byweight at which the viscosity is a maximum. In sodium alginatedispersions of 0.1% or lower this 1:15 ratio corresponds approximatelyto the precipitation of calcium alginate. In more concentrated sodiumalginate dispersions, say 0.2% or higher, this 1:15 ratio corresponds tothe approx- L imate maximum calcium concentration for the whether or nota decrease or increase in viscosity will be obtained depends upon therelative amounts of metal, alginate, and phosphate glass present.Accordingly it is necessary, in order properly to control the viscosityof the solution being treated to control the concentrations of themetal, alginate and phosphate glass in the solution.

The results to be achieved and the need for controlling the abovementioned factors is well exemplified by the production of chocolatemilk drinks for which the process of my invention is eminentlysatisfactory. As was stated above sodium alginate is now used quitewidely as a stabilizer for chocolate flavored milk drinks in order tokeep the cocoa particles in suspension in the milk. The sodium alginatemay be added dry or predissolved or made into a dispersion in water ormilk and the dispersion added to the milk along with the otheringredients, or the sodium alginate may be incorporated in the chocolateflavoring syrup or other ingredients which are added to the milk. Whilethe use of sodium alginate as a stabilizer for chocolate milk has comeinto quite wide use it is open to serious objections, since, in order toget viscosities high enough to suspend the chocolate powder, excessivequantities of alginate are required. This is not only costly, but alsoa. slimy body or unpleasant taste is imparted to the chocolate milk,rendering it unpalatable.

I have found that in the case of chocolate milk drinks thesedifiiculties can be overcome by employing a molecularly dehydratedphosphate in conjunction with the sodium alginate. For example, inpreparing chocolate milk drinks I may add sodium alginate andmolecularly dehydrated phosphate to the cocoa syrup and then add this tothe milk. The preferred molecularly dehydrated phosphate is the sodiumphosphate glass commonly known as Grahams salt, which has a mol ratio ofNazO to P205 of 1:1 or its commercial form known under the trade nameCalgen which has a mol ratio of NazO to P205 of 1121. Other phosphateglasse having difierent ratios of NazO to P205 may be employed, or thecrystalline molecularly dehydrated phosphates, such as the alkali-metalpyrophosphates or tripolyphosphates may be used. The more nearly neutralmolecularly dehydrated phosphates are preferred to avoid alkalinity inthe product. For convenience in describing the invention further I shallrefer to sodium metaphosphate, meaning by this expression the sodiumphosphate glass commonly known in the trade as Calgon which is thecommercial form of Grahams salt, it being I.)

understood that glasses having other ratios of alkali-metal oxide toP205 or the other molecularly dehydrated phosphates may be employed.

Where, according to my invention, both sodium alginate and sodiummetaphosphate are added to the milk the sodium metaphosphate when addedin proper amount controls the viscosity of the alginate, wherebyincreased viscosity may be obtained using relatively smaller amounts ofalginates. Thus the amount of expensive sodium alginate required forstabilization is minimized, the viscosity is easily and accuratelycontrolled and a pleasingly palatable milk product free of sedimentationand stratification is produced. Table I shows the effect on viscosity ofadding phosphate glass to a chocolate flavored milk drink containingalginate.

TABLE I Al l i l i R l t ginate p oso ate e a ive percent glass (1.1:1),viscosity Remarks percent 0. 0 0. 0 100 Sediment. 0. 0 0. 2 101 D0. 0. 10. 0 105 Two layers 0. 2 0.0 109 Do. 0. l 0. 2 124 Perfect suspension.0. 2 0. 2 183 Do.

made from concentrated milk or from powdered milk. It may be used intreating any preparation containing a substantial amount of soluble milksolids either alone or with other materials. It may be used, forexample, in making ice cream or other frozen milk or cream products.

As I have previously stated, materials other than the alginates havebeen used as stabilizers in milk products, for example, pectin andgelatin. I have found, however, that neither of these materials issuitable for use in treating aqueous dispersions according to myinvention. I have found that only the alginates have the property ofcombining with the metal compounds and molecularly dehydrated phosphatesto produce a variable and controlled viscosity. Comparative viscositytests using pectin, gelatin and alginate on ice cream mixes produced theresults shown in the following table:

1 Sodium phosphate glass (1.1:1).

Tests of comparative stabilizing effect and viscosity were made withhalf-pint chocolate milk combinations using sodium alginate, pectin andgelatin with the following results:

TABLE III A.Sodzum algmate Percent sodium Percent phos- Appearance in8-ounce bottle after lye alginate phate 16 hrs. at 45 F.

glass cosity 1.1:1 F

0. 0 0.0 chocolate sediment 0. 1 0. 0 chocolate sediment. 102 0. l 0.1Slight chocolate sedimen 112 0.1 0.2 do 114 0. 1 0.3 Not completelyuniform 117 0. 2 0. 0 chocolate sediment-.. 104 0. 2 0. 1 Completedispersion 128 0.2 0.2 do .1 137 0.2 0.3 do 154 0. 3 0.0 chocolatesediment. 110 0. 3 0. 1 MottledSemi-gcl 346 0. 3 0. 2 CompletedispersionSem gel 595 0. 3 0. 3 d 403 B.Pectm (1 50 grade) Percentsodium i Percent phos- Appearance in 8-ounce bottle after lye alginatephate 16 hrs. at 45 F. lass 2 5 1.111 (55 0. 0 0. 0 100 0. 1 0. 0 104 0.1 0. l 105 0. 1 0. 2 106 0. l 0. 3 109 0. 2 0. 0 107 0. 2 0. l 107 O. 20. 2 110 0. 2 O, 3 113 0. 3 0. 0 111 0. 3 0. 1 112 0.3 0.3 ,do 117 0.50.0 chocolate sediment 119 0. 5 0. 1 chocolate sediment 1. 121 045 0.2(o 125 0. 5 0.3 chocolate sediment 127 C'.-Gelatm (225 bloom) Percentsodium 5 3? Percent phos- Appearance in 8-ounce bottle after :1: gelatinphate 16 hrs. at 45 F. g i

la 1.11 M

0.0 0.0 chocolate sediment 100 0.1 0.0 dO 102 0. 1 0. 1 104 0. 1 0. 2107 0. 1 0. 3 109 0. 2 0. 0 105 0. 2 0. 1 108 0. 2 0. 2 111 0. 2 0. 3113 0. 3 0. 0 115 0. 0. 1 118 0. 3 0. 2 125 0. 3 0. 3 125 0. 5 0. 0 0 0.5 0. 1 175 0. 5 0. 2 179 0. 5 0. 3 175 D.-No stabilizer Percent sodium5- 5 Perceut phos- Appearance in 8-ounce bottle after e stabilizer phate16 hrs. at 45 F. g

glass 0 0.0 0. 0 chocolate sediment 100 0.0 0.1 .d0 102 0. 0 0. 2 104 0.0 0. 3 106 It is apparent from a careful consideration of the abovetables that only the alginate stabilized ice cream mixes and chocolatemill: compositions showed the remarkable viscosity eliect which ischaracteristic of my invention. In the case of the gelatin and pectinstabilized ice cream mixes the viscosities upon addition of the sodiumphosphate glass Were irregular and unpredictable whereas with thealginate stabilizer upon the addition of the sodium phosphate glass theviscosity regularly decreased as the concentration of sodium phosphateglass increased. In the case of chocolate milk drinks the onlycompletely dispersed, nongelatinous mixture resulted from the use ofsodium phosphate glass and alginate.

The method of treating aqueous dispersions to control their viscosityhas various applications other than that of controlling the viscosity ofmilk products. I have found that the process of my invention may beapplied to the preparation of abrasive polishing compostiions. Suchcompositions usually contain powdered pumice or other inert insolubleabrasive substance in a suspending medium. The abrasive polishingcompositions may be sold in the form of creams, pastes, or jellies, oras a powder to be formed into a suspension with water before use. Onedifiiculty with such pastes or suspensions now on the market is that theabrasive has a tendency to settle out of the suspension to form a layerat the bot tom of the container in which it is held. According to myinvention I overcome this tendency by adding to the suspension or to thepowder from which the suspension is to be made, alginate, a compoundyielding ions of a metal which modifies the viscosity of the alginatedispersion and sodium metaphosphate or other molecularly de hydratedalkali-metal phosphate in an amount to give the desired viscosity. It ispossible, and may at times be desirable to add the metal ion required asa part of the alginate, for example, as iron alginate.

Another way of overcoming the tendency of iii) abrasives to settle whena powder is made into a paste or a dispersion with water, is to add tothe powder or to the suspension, calcium alginate or otherwater-insoluble, alginate and sodium metaphosphate. The sodiummetaphosphate reacts with the water-insoluble alginate, therebyincreasing the viscosity of the suspension.

The invention may also be employed in the production, of textileprinting pastes. These pastes contain a color body, Water as a vehiclefor the color body, and an alginate such as sodium alginate. Theviscosity and suspending power of the vehicle may be controlled,according to my invention, by including regulated amounts of sodiummetaphosphate and, when desired, a compound yielding metal ion whichmodifies the viscosity of the vehicle in such printing pastes. Theinclusion of sodium metaphosphate in the printing paste preventsexcessive viscosity due to metals incidentally present, while theaddition of the compound yielding metal ion is used to control theviscosity at its optimum value. Thus the suspending power of the pasteor suspension on the color body may be accurately controlled. Inaddition to the aforementioned advantages, the sodium metaphosphateproduces a more hemogeneous paste.

For many uses it is desirable to obtain an alginate solution of maximumviscosity by the use of a minimum amount of the expensive sodiumalginate. This may be done by adding a calcium compound or other metalcompound to the sodium alginate solution, but it is difficult to producemaximum viscosity by this method because after maximum viscosity hasbeen reached, any excess metal ion causes precipitation of thewater-insoluble metal alginate, and the viscosity of the solution lowersvery rapidly and the mixture becomes lumpy and contains precipitatedalginate particles. I have found that I can produce an alginatedispersion having maximum viscosity by adding water-soluble metalcompound in such an amount as to go somewhat beyond the point of maximumviscosity, thereby causing precipitation of metal alginate, andthereafter adding sodium metaphosphate in regulated amounts in order tobring back: the dispersion to its maximum viscosity. The use of sodiummetaphosphate for regulating the viscosity of an alginate dispersioncontaining metal ion, is not limited to causing precipitation ofinsoluble metal alginate and thereafter adding sodium metaphosphate toincrease the viscosity of the solution. For instance, if it is desiredto produce a certain viscosity from a sodium alginate dispersion by theaddition of metal compound, sodium metaphosphate may be added to thedispersion if, through inadvertence, the amount of metal com pound addedwas in excess of that required to produce the desired viscosity but lessthan that required to precipitate insoluble metal alginate. In this casethe heavy-metal compound increased the viscosity to an undesirableextent. The addition, of the proper amount of sodium metaphosphate willlower the viscosity to the point desired. Thus the addition of sodiummetaphosphate will either increase or decrease the viscosity of analginate dispersion containing metal ion, depending on the ratio ofsodium metaphosphate to metal ion.

Another way of producing an alginate solution of maximum viscosity or ofany desired viscosity is to add calcium alginate Or otherwater-insoluble metal alginate to water, and then add regulated amountsof sodium metaphosphate. As the amount of sodium metaphosphate added isincreased the metal alginate goes into colloidal dispersion or solutionand the viscosity of the dispersion increases up to a maximum and thendecreases. The amount of metaphosphate added is selected so as to givethe optimum viscosity within this range. instead of first forming adispersion of water-insoluble metal alginate and thereafter addingsodium metaphosphate to the dispersion, I may make a mixure of metalalginate and sodium metaphosphate in the proportions required forproducing the desired viscosity of the dispersion, or I may add metalcompound and sodium metaphosphate in solution to a sodium alginatedispersion.

If it is desired to produce an alginate solution which has an initiallow viscosity and to increase the viscosity of the solution slowly, Imay start with a sodium alginate solution and add to it a slowly-solublecompound yielding ions of calcium 01' other metal which modify theviscosity of alginate dispersions. As the slowly-soluble compounddissolves, introducing metal ion progressively into the solution, theviscosity of the solution increases. Any slowly-soluble metal compoundwhich modify the viscosity of alginate dispersions may be employed, buta preferred ma terial for this purpose is a phosphate glass of a metalwhich modify the viscosity of alginate dispersions or of a metal whichmodify the viscosity of alginate dispersions and an alkali metal, forexample a sodium-calcium phosphate glass. As the phosphate glass slowlydissolves and reverts, at a rate depending upon the particularconditions, to orthophosphate, metal ion is made available for reactionwith the sodium alginate to increase the viscosity of the dispersion.

D1 describing; the invention I have usually referred to sodiummetaphosphate or sodium phosphate glass, but it is to be understood thatin all cases I may use other molecularly dehydrated phosphates, such asthe pyrophosphates or tripolyphosphates. The molecularly dehydratedphosphates will usually be water-soluble alkalimetal or ammoniumphosphates, although I may employ where desired the less readily solublesalts containing both alkali metal and metal which modify the viscosityof alginate dispersions or the mixed phosphate glasses of one or morealkali metals and one or more metal which modify the phate ormolecularly dehydrated phosphate compositions, whether glassy orcrystalline, containing alkali metal or ammonia and one or more metalswhich modify the viscosity of alginate dispersions.

The invention is not limited to the particular embodiments described butmay be otherwise embodied or practiced within the scope of the followingclaims:

Iclaim:

1. The process of treating an aqueous dispersion having as oneconstituent a water-soluble metal compound having the property ofmodifying the viscosity of an alginate dispersion, which comprisesadding to the dispersion a molecularly dehydrated phosphate in an amountso related to the total metal in solution that some but not all of themetal will be sequestered, leaving some available metal ion in solution,and adding a water-soluble alginate to the dispersion whereby the freemetal ion reacts with the alginate, the

i6 amount of free metal ion being so regulated that a portion only ofthe alginate will be reacted.

2. The process of treating an aqueous dispersion having as oneconstituent a water-soluble metal compound of the group consisting ofcalcium, barium, strontium, silver, copper, zinc, aluminum, titanium,tin, lead, mercury, vanadium, antimony, chromium, manganese, iron,cobalt, nickel and lanthanum, which comprises adding to the dispersion amolecularly dehydrated phosphate in an amount so related to the totalmetal in solution that some but not all of the metal will besequestered, leaving some available metal ion in solution, and addingsodium alginate to the dispersion whereby the free metal ion reacts withthe alginate, the amount of free metal ion being so regulated that aportion only of the alginate will be reacted with the metal compound.

3. The process of treating an aqueous dispersion having as oneconstituent a water-soluble calcium compound which comprises adding tothe dispersion a molecularly dehydrated phosphate in an amount sorelated to the total calcium in solution that some but not all of thecalcium will be sequestered, leaving some available calcium ion in thesolution and adding sodium alginate to the dispersion whereby the freecalcium ion reacts with the alginate, the amount of free calcium ionbeing so regulated that a portion only of the alginate will be reacted.

l. The process of treating an aqueous dispersion of milk solids whichcomprises adding to the dispersion a molecularly dehydrated phosphate inan amount so related to the total calcium content or" the milk solidsthat some but not all of the calcium will be sequestered, leaving someavailable calcium ion in solution, and adding sodium alginate to thedispersion whereby the free calcium ion reacts with the alginate, theamount of free calcium ion being so regulated that a portion only of thealginate will be reacted.

5. The process of treating an aqueous dispersion having as constituentsa water-soluble metal compound having the property of modifying theviscosity of an alginate dispersion and a finely divided solid materialin aqueous suspension to stabilize the suspension which comprises addingto the dispersion a molecularly dehydrated phosphate in an amount sorelated to the metal in solution that some but not all of the metal willbe sequestered, leaving some available metal ion in the solution, andadding a water-soluble alginate to the dispersion whereby the free metalion reacts with the alignate, the amount of free metal ion being soregulated that a portion only of the alginate will be reacted.

6. The process of treating an aqueous dispersion having as constituentsa water-soluble metal compound having the property of modifying theviscosity of an alginate dispersion and a color body in aqueoussuspension to form a textile printing paste, which comprises adding tothe dispersion a molecularly dehydrated phosphate in an amount sorelated to the metal in solution that some but not all of the metal willbe sequestered, leaving some available metal ion in the solution, andadding a water-soluble alginate to the dispersion whereby the free metalion reacts with the alginate, the amount of free metal ion being soregulated that a portion only of the alginate will be reacted.

7. A process of treating an aqueous dispersion having as constituents awater-soluble metal compound, an alginate dispersion and an abrasivematerial in aqueous suspension to form an abrasive paste, whichcomprises adding to the dispersion a molecularly dehydrated phosphate inan amount so related to the metal in solution that some but not all ofthe metal will be sequestered, leaving some available metal ion in thesolution, and adding a water-soluble alginate to the dispersion wherebythe free metal ion reacts with the alginate, the amount of free metalion being so regulated that a portion only of the alginate will bereacted.

8. A process of treating an aqueous dispersion of milk solids and cocoaparticles to stabilize the dispersion by preventing the cocoa, particlesfrom settling which comprises adding to the dispersion a molecularlydehydrated phosphate in an amount so related to the total calciumcontent of the milk solids that some but not all of the calcium will besequestered, leaving some available calcium ion in solution, and addingsodium alginate to the dispersion whereby the free calcium ion reactswith the alginate, the amount of free calcium ion being so regulatedthat a portion only of the alginate will be reacted.

9. The process of treating an aqueous dispersion having as oneconstituent a water-soluble calcium compound which comprises adding tothe dispersion a sodium phosphate glass in an amount so related to thetotal calcium in solution that some but not all of the calcium will besequestered leaving some available calcium ion in the solution andadding sodium alginate to the dispersion whereby the free calcium reactswith the alginate, the amount or free calcium being so regulated that aportion only of the calcium will be reacted.

10. The process of treating an aqueous dispersion of milk solids whichcomprises adding to the dispersion a sodium phosphate glass in an amountso related to the total calcium content of the milk solids that some butnot all of the calcium will be sequestered, leaving some availablecalcium ion in solution, and adding sodium alginate to the dispersionwhereby the free cal- :ium ion reacts with the alginate, the amount offree calcium ion being so regulated that a porzion only of the alginatewill be reacted.

11. The process of controlling the viscosity of iispersions made fromwater-soluble alginates vhich comprises adding to said dispersions anolecularly dehydrated alkali metal phosphate LIld a water-soluble metalcompound having the )roperty of modifying the viscosity of an alginateiispersion, the relative amounts of molecularly lehydrated alkali metalphosphate and water- ;oluble metal compound being so regulated that a)ortion only of the alginate will be reacted with he metal compound. I

12. The process of stabilizing a suspension of olid particles in a milkproduct which comprises ncorporating therein a water-soluble alginateind a molecularly dehydrated alkali metal phoshate in such proportionsthat the amount of free alcium ion is so regulated that a portion onlyof h alginate will be reacted.

13. The process of adjusting the viscosity of a later-soluble alginatedispersion which comrises adding thereto a Water-soluble compound f anature having the property of modifying the iscosity of the alginatedispersion in amount 1 excess of that required to produce the requirediscosity and threaft'er adding to the dispersion molecularly dehydratedalkali metal phosphate 1 an amount sufficient to obtain the desirevisosity.

14'. The process of inhibiting the precipitation of metal alginates froma solution containing metal ions in an amount suificient to precipitatemetal alginates upon addition of a water-soluble alginate to thesolution which comprises adding a molecularly dehydrated alkali metalphosphate to said solution.

15. A stabilized aqueous dispersion containing milk solids comprising awater soluble alginate and a sufficien-t amount of molecularlydehydrated phosphate to regulate the amount of alginate which iscombined with the calcium of the milk solids.

16. A stabilized aqueous dispersion of cocoa particles and milk solidscomprising a watersoluble alginate and an amount of molecularlydehydrated alkali metal phosphate sufficient to permit a portion but notall of the alginate to react with the calcium of the milk solids.

17. A textile printing paste comprising a suspension of a color body inan aqueous vehicle a water-soluble alginate, a water-soluble metalcompound having the property of modifying the viscosity of an alginatedispersion and a molecularly dehydrated phosphate in an amount such thata part but not all of the alginate will be reacted with the metal ion ofthe metal compound.

18. An abrasive polishing composition comprising an abrasive suspendedin an aqueous medium containing a water-soluble alginate, awater-soluble metal compound having the property of modifying theviscosity of an alginate dispersion and a molecularly dehydratedphosphate in an amount such that a portion but not all of the alginatewill be reacted with the metal ion of the metal compound.

19. The process of treating an aqueous dispersion having as oneconstituent a water-soluble metal compound having the property ofmodifying the viscosity of an alginate dispersion which comprises addingto the dispersion, molecularly dehydrated phosphate having an alkalimetal oxide to P205 ratio of between about 1:1 and 2:1 in amount sorelated to the metal in solution that some but not all of the metal willbe sequestered leaving some available metal ion in solution, and addinga water-soluble alginate to the dispersion whereby the free metal ionreacts with the alginate, the amount of free metal ion being soregulated that a portion only of the alginate will be reacted.

20. The process of treating an aqueous dispersion of milk solids whichcomprises adding to the dispersion a molecularly dehydrated phosphatehaving an alkali metal oxide to P205 ratio of between about 1:1 and 2:1in amount so related to the total calcium content of the milk solidsthat some but not all of the calcium will be sequestered leaving someavailable calcium ion in solution, and adding sodium alginate to thedispersion whereby the free calcium ion reacts with the alignate, theamount of free calcium ion being so regulated that a portion only of thealginate will be reacted.

21. The process of treating an aqueous dispersion having a oneconstituent a water-soluble calcium compound which comprises adding tothe dispersion a molecularly dehydrated phosphate having an alkali metaloxide to P205 ratio of between about 1:1 and 2:1 in amount so related tothe total calcium in solution that some but not all of the calcium willbe sequestered leaving some available calcium ion in the solution, andadding sodium alginate in the solution whereby the free calcium ionreacts with the alginate, the

amount of free calcium ion being so regulated that a portion only of thealginate will be reacted.

22. The process of treating an aqueous dispersion having as constituentsa water-soluble metal compound having the property of modifying theviscosity of aliginate dispersion and a finely divided solid material inaqueous suspension to stabilize the suspension which comprises adding tothe dispersion a molecularly dehydrated phosphate having an alkali metaloxide to P205 ratio of between about 1:1 and 2:1 in an amount so relatedto the material in solution that some but not all of the metal will besequestered, leaving some available metal ion in the solution, andadding a water-soluble alginate to the dispersion whereby the free metalion reacts with the alginate, the amount of free metal alignate being soregulated that a portion only of the alginate will be reacted.

23. The process of treating an aqueous dispersion having as oneconstituent a water-soluble metal compound having the property ofmodifying the viscosity of an alginate dispersion which comprises addingto the dispersion a molecularly dehydrated phosphate having an alkalimetal oxide to 1 :05 ratio of about 1.1:1 in an amount so related to themetal in solution that some but not all of the metal will be sequesteredleaving some available metal ion in solution, and adding a water-solublealginate to the dispersion whereby the free metal ion reacts with thealginate, the amount of free metal ion being so regulated that a portiononly of the alginate will be reacted.

24. The process of treating an aqueous dispersion of milk solids whichcomprises adding to the dispersion a molecularly dehydrated phosphatehaving an alkali metal oxide to P205 ratio of about 11:1 in amount 50related to the total calcium content of the milk solids that some butnot all of the calcium will be sequestered leaving some availablecalcium ion in solution and adding sodium alginate to the dispersionwhereby the free calcium ion reacts with the alginate, the amount offree calcium ion being so regulated that a portion only of the alginatewill be reacted.

25. Theprocess of treating an aqueous dispersion having as oneconstituent a water-soluble calcium compound which comprises adding tothe dispersion of molecularly dehydrated phosphate having an alkalimetal oxide to P205 ratio of 11:1 in an amount so related to the totalcalcium in solution that some but not all of the calcium will besequestered leaving some available calcium ion in the solution andadding sodium alginate in the solution whereby the free calcium ionreacts with the alginate, the amount of free calcium ion being soregulated that a portion only of the alginate will be reacted.

26. The process of treating an aqueous dispersion having as constituentsa water-soluble metal compound having the property of modifying theviscosity of alginate dispersion and a finely divided solid material inaqueous suspension to stabilize the suspension which comprises adding tothe dispersion a molecularly dehydrated phosphate having an alkali metaloxide to P205 ratio of about 1.1:1 in an amount so related to thematerial in solution that some but not all of the metal will besequestered, leaving some available metal ion in the solution, andadding a watersoluble alginate to the dispersion whereby the free metalion reacts with the alginate, the amount of free metal alignate being soregulated that a portion only of the alginate will be reacted.

27. A process of treating an aqueous dispersion of milk solids and cocoaparticles to stabilize the dispersion by preventing the cocoa particlesfrom settling which comprises adding to the dispersion a molecularlydehydrated phosphate having an alkali metal oxide to P205 ratio of 1.1:1in an amount "so related to the total calcium content of the milk solidsthat some but not all of the calcium ion will be sequestered leavingsome available calcium ion in solution, and adding sodium alginate tothe dispersion whereby the free calcium ion reacts with the alginate,the amount of free calcium ion being so regulated that a portion only ofthe alginate W111 be reacted.

28. A stabilized aqueous dispersion of cocoa particles and milk solidscomprising a watersoluble alginate and an amount of a molecularlydehydrated alkali metal phosphate having an alkali metal oxide to P205ratio of 1.1:1 suificient to permit a portion but not all of thealginate to react with the calcium of the milk solids.

29. A stabilized aqueous dispersion containing milk solids comprising awater-soluble alginate and a sufilcient amount of a molecularlydehydrated phosphate having an alkali metal oxide to P205 ratio of 1.1:1to regulate the amount of alginate which is combined with the calciiunof the milk solids.

30. A stabilized aqueous dispersion comprising a water-soluble metalcompound having the property of modifying the property of an alginatedispersion, a suspension of a finely divided solid material and anamount of a molecularly dehydrated alkali metal phosphate having analkali metal oxide to P205 ratio of about 1.111 sufiicient to permit aportion but not all of the alginate to react with the metal compound.

CHARLES T. ROLAND.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,897,892 Draisbach Feb. 14, 1933 2,064,387 Schwartz Dec. 15,1936 2,081,273 Hoermann et a1. May 25, 1937 2,097,230 Lucas Oct. 26,1937 2,097,231 Lucas Oct. 26, 1937 2,103,411 Frieden et a1. Dec. 28,1937 2,135,054 Schwartz Nov. 1, 1938 2,207,299 Mnookin July 9, 19402,216,485 Brandt Oct. 1, 1940 2,253,389 Mnookin Aug. 19, 1941 2,267,911Grettie et al. Dec. 30, 1941 2,405,861 Tod Aug. 13, 1946 FOREIGN PATENTSNumber Country Date 446,529 Great Britain Apr. 30-, 1936 OTHERREFERENCES Sommer: The Theory and Practice of Ice Cream Making, 3rd ed.,pages 428-430. (Published by the author at Madison, Wis., 1938.)

1. THE PROCESS OF TREATING AN AQUEOUS DISPERSION HAVING AS ONECONSTITUENT A WATER-MODIFYMETAL COMPOUND HAVING THE PROPERTY OFMODIFYING THE THE VISCOSITY OF AN ALGINATE DISPERSION, WHICH COMPRISEDADDING TO THE DISPERSION A MOLECULARLY DEHYDRATED PHOSPHATE IN AN AMOUNTTHAT SOME BUT NOT TO THE TOTAL METAL IN SOLUTION THAT SOME BUT NOT ALLOF THE METAL WILL BE SEQUESTERED, LEAVING SOME AVAILABLE METAL ION INSOLUTION, AND ADDING A WATER-SOLUBLE ALGINATE TO THE DISPERSION WHEREBYTHE FREE METAL ION REACTS WITH THE ALGINATE, THE AMOUNT OF FREE METALION BEING SO REGULATED THAT A PORTION ONLY OF THE ALGINATE WILL BEREACTED.